1. Physics Investigation Formative Feedback 23/05/16

2. Needed For Achieved (all six points) 1.Independent variable Length of helicopter wingspan (measured in cm). 2.Dependent variable Time taken for helicopter to fall to the ground (measured in s). 3.Methods Listed description of how the investigation was performed.

3. 4.Results At least four different wingspan values are listed. Times are recorded and averaged. Units correctly stated. 5.Graph Length of wingspan on x-axis; time on y-axis. Axes are labelled, with units. Data is mostly plotted accurately. Line graph is relevant to plotted data. 6.Conclusion – based on the data. “As the wingspan of the helicopter was shortened, the time taken for the helicopter to fall to the ground also decreased”.

4. Needed for Merit (all five points) 1.Controlled variables Must have four, including drop height. 2.Accuracy Repeating each test three times and averaging results; OR measuring at eye level to reduce parallax error. 3.Results Table shows data for three trials plus average.

5. 4.Graph Scales are appropriate and easy to read. The graph covers 80% of the grid provided. An accurate line of best fit. Gradient is correctly calculated and written in decimal form (3sf).

6. FORMULATING A LINEAR EQUATION x x x x x x x x 12 3 11 2 Rise = y 2 – y 1 = 12 – 3 = 9 y2y2 y1y1

7. x x x x x x x x 12 3 11 2 Run = x 2 – x 1 = 11 – 2 = 9 Gradient (m) = rise run = 9 = 1 9 x2x2 x1x1 Rise = y 2 – y 1 = 12 – 3 = 9

8. 4.Graph Scales are appropriate and easy to read. The graph covers 80% of the grid provided. An accurate line of best fit. Gradient is correctly calculated and written in decimal form (3sf). 5.Conclusion Based on the data collected, relates back to the purpose. “As the wingspan of the helicopter shortened, the speed with which it fell to the ground increased”. [Negative correlation: the shorter the wingspan the faster it falls]

9. For Excellence (two of the following points) Discussion 1.Justify accuracy-improving techniques (why are they important) Repeating and averaging measurements of time were needed because reaction time meant that each measurement could have been slightly different between trials. Needed to hold the helicopter at eye level to the ruler for greater accuracy. 2.Justify why a specific variable needs to be controlled. Example: The helicopter needs to be dropped from the same height each time to ensure the same forces are acting on it each time. 3.Describe difficulties encountered and how they were overcome.

10. 4.Physics principles Forces acting on the helicopter are F gravity and F air resistance. Greater wingspan provides greater surface area for air resistance to act. Greater F air resistance = reduced F net in the direction of gravity. Because a change in F net results in change in speed, reduced F net in the direction of gravity (caused by a greater wingspan) led to the helicopter being slower to reach the ground.